This is something I've been wondering for some time: I notice that some op-amps are not specified to be unity gain stable. Couldn't you just set the gain to maybe 5 or 10, and then run the output to a matching 5 or 10 resistive voltage divider for a "virtual" unity gain effect?

You could, but of course you'll increase the effective output impedence by doing this, making systems like active filters troublesome to design. In fact, most systems/stages requiring a unity gain are going to be severely restricted by having this increased output impedence, the fix for which is a unity gain buffer following it (making it totally irrelevant!)

I should ask specifically what it is you are trying to do, what this unity gain application is?

Well, you'll get a bit of additional noise due to the excess gain, and the voltage divider (just as with a regular attenuator) will result in the chip being driven from a bit higher source impedance which will increase distortion a bit.

This is something I've been wondering for some time: I notice that some op-amps are not specified to be unity gain stable. Couldn't you just set the gain to maybe 5 or 10, and then run the output to a matching 5 or 10 resistive voltage divider for a "virtual" unity gain effect?

Seems too simple. I'm probably missing something.

Yes, but why bother?

It is not the amp design itself which has a specific stability, but how much internal compensation is applied.

I am not sure there are any op-amps available which do not have a version which is unity gain stable.